Answer: Option D. -> Thread
:
D
Foot is not a standard instrument of measurement. The length of the foot may vary from person to person. So it can't be used to measure the length of a curved line.
A thread is flexible. It can be bent easily to cover the curved line. It can then be straightened on a scale to measure the length.
Measuring cylinder is used to measure volume of liquids.
Thermometer is used to measure and indicate temperature of any object.

Answer: Option A. -> $5.924km$
:
A
We know $1000m=1km$
$5924m=\frac{5924}{1000}km$
$5924m=5.924km$

Answer: Option B. -> False
:
B
When we see the trees from a moving train, their position is changing with respect to us. Hence, they appear to be moving. On the other hand, the position of co-passengers is not changing with respect to us, hence they appear to be stationary.

Answer: Option D. -> Cubic metre
:
D

Metre, kilogram and kelvin are fundamental units. Metre is the fundamental unit of length, kilogram is the fundamental unit of mass and kelvin is the fundamental unit of temperature.
Cubic metre is a unit of volume and is obtained from the unit of length ($m$).

Answer: Option C. -> Periodic motion.
:
C

A motion that repeats itself after equal interval of time is called as periodic motion. For example, the motion of a pendulum and the motion of the Earth around the Sun can be considered as a periodic motion since it repeats itself after an equal interval of time.

Answer: Option A. -> True
:
A

When a particle moves along the circumference of a circle it is said to be in a circular motion. The tip of the second's hand is doing circular motion as it is moving around a circular path with respect to the centre of the clock.

Answer: Option B. -> False
:
B

They may encounter some human error, for example, parallax error. Parallax error arises when the reading is taken from random angles. It is a non-technical (human) error in which there is a difference in the readings if the readings are taken at different angles from the line of sight. Hence, to avoid this error, we must always take the readings by placing our eyes perpendicularly above the markings.

Answer: Option B. -> False
:
B

The unit of length should be chosen such that it is constant and same for everyone. SInce, everyone's footstep is not same, it cannot be used as a unit of length.

Answer: Option B. -> False
:
In Rectilinear or Linear motion, the object moves along a straight path.

Answer: Option B. -> False
:

1 millimeter < 1 centimeter < 1 meter < 1 kilometer.