What the answer be this for one?

What term best describes a line and a point that lie in the same plane? a. congruent b. coplanar c. collinear d. equal

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?

Me d is also an option but i couldn't get it in the picture