Measuring the diameter of a specific object might include which pair of SI units
A. Gram, second
B. Kilogram, ampere
C. Centimeter, meter
D. Candela, mole

Well, the diameter of a circle is simply a length, so your measurement will have units of length.  We just have to find an answer that has only units of length.

A).  gram, second . . . mass and time.  That can't be it.

B).  kilogram, ampere . . . mass and current.  That can't be it.

C).  centimeter, meter . . . both lengths. This one is looking good.

D).  candela, mole . . . light intensity and some chemical thing. That can't be it.

So it can't be anything else on this list but C .

the word that best describes martin luther king jr.'s tone in the video is dignified

martin luther king, jr. was a social activist and baptist minister who played a key role in the american civil rights movement from the mid-1950s until his assassination in 1968. the video shows his manner and attitude having or showing a composed or serious manner that is worthy of respect so dignified is the correct answer

beta is electron from nucleus

something from nucleus has changed, but charge must be same for cons of charge