5. M
5
.
Given: l is in plane M
t is on line 1
Conclusion: t is in plane M.
The general principle that justifies the conclusion is
a. postulate: a line contains at least two points
b. postulate: if a plane contains a line, it contains the point of the line
c. theorem: if two lines intersect, then one plane contains both lines
d. definition of line segment