Using figure $9-13,$ what is the Benchmark elevation at IP #$4?$

$\backslash$table$[[$Figure $9-13$ Field Notes For Calculation Question$],[\backslash$table$[[,,$BS$,,,],[$IP$,$BM Elev.,Rod Reading,HI$,$Rod Reading,TP Elev.$],[$#$1,877\mathrm{.}26,7\mathrm{.}45,,3\mathrm{.}1,],[$#$2,,7\mathrm{.}12,,1\mathrm{.}1,],[$#$3,,4\mathrm{.}44,,2\mathrm{.}17,],[$#$4,???,,,,]]]]$

Select one:

a$.864\mathrm{.}62$

b$.889\mathrm{.}90$

c$.902\mathrm{.}64$

d$.896\mathrm{.}27$