Reversible lanes are marked with unique signs, signals and markings, such
a) a flashing yellow x, which means use this lane only for a right turn
b) a solid yellow x, which means stay in the lane but slow down
c) a red x, which means the lane is closed
d) a flashing red x, which means to prepare to stop

Option A

Explanation:

The reversible traffic lanes are a regulatory tool/mechanism to control the traffic in rush hour where the directions of traffic are kept opposite to each other at a particular time of the day. So, symbolically they are represented by pavement markings along with special lane signals, symbols, and sign which are as follows –  

a)Solid white line marking the edge of the pavement

b)Stop lines, crosswalks and parking spaces are marked by white lines

c)Symbols in white color

d)Single yellow line marks to highlight the left edge of one-way road and all divided road.  

e)  Yellow-colored marked curbs

f)Central  lane marking arrow  

Hence, option A is correct

the element that provides strength to the exoskeletons of clams and oysters is phosphorus. this is so because calcium carbonate is the main component in the shells.

explanation: