In a two-dimensional motion, instantaneous speed v0 is a positive constant. Then which of the following are necessarily true?

It is given that we need to identify a necessarily true statement.

As there is no information of direction, therefore even though the particle’s speed is constant it can be accelerating. For example in a circular motion.

Acceleration depends on the velocity which in-turn depends on its magnitude and direction; therefore no condition can be applied on acceleration.

It could be that particle is moving in a straight line, therefore with a surety, we can’t say the particle is moving in a circular direction.

But, acceleration will always be in the plane of motion only.