Premises:
if a quadrilateral has opposite sides that are parallel, then it is a parallelogram.
a rhombus is a quadrilateral where the opposite sides are parallel.
conclusion:
a rhombus is a parallelogram.
which statement best describes this argument?

the argument is invalid because the conclusion does not follow the premises.

the argument is invalid because the premises are not true.

the argument is valid by the law of detachment.

the argument is valid by the law of syllogism.

The argument is valid by the law of syllogism

Step-by-step explanation:

Given :-If a quadrilateral has opposite sides that are parallel, then it is a parallelogram.

A rhombus is a quadrilateral where the opposite sides are parallel.

then by law of syllogism (reasoning of transitivity) the conclusion is "A rhombus is a parallelogram."

Law of syllogism is similar to reasoning to transitivity i.e. if a=b and b=c then a=c.

sorry i dont know my friend

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this