periods on the periodic table are arranged
oa) in horizontal rows.
ob) by order of density.
oc) in vertical columns
od) in no particular order.

A) in horizontal rows  

Explanation:

The Periodic Table is arranged into 18 vertical Groups and seven horizontal Rows or Periods.

For example, the red arrow in the picture below shows Row 4 or the 4th Period.

B) and D) are wrong. The Periodic Table is arranged according to increasing  atomic number.

C) is wrong. The Groups are arranged in vertical columns.

passed in september 1935, these laws are known as nuremberg laws.   they forbid jews from marrying but not directly forced them to divorce aryans. what is most noticeable is the fact that the jews were defranchised, meaning by this that they were not expected to have any civil rights, including the right to vote. the right answer is deprived of the right to vote.

no, the red giant is the hottest with 2.00.000.000 degrees celsius. while the white dwarf only 25,000 degrees celsius.